This is the object of this peculiar construction, and not,
as some engineers suppose, simply to make an odd way of doing things.
And the object of it all is to give at all cut offs the same amount of
travel, so that there might be no unequal wear to bring about a leak,
to prevent which a perfect balancing has been sacrificed.
Referring to the valve and this engine as to how it will satisfy our
requirements of a perfect valve gear, we find that the first
requirement of a rapid and full opening is met, in that the opening
occurs when the main eccentric is moving very rapidly, yet not its
fastest, and while this opening will be very satisfactory, it is not
so rapid an opening as is obtained in some other forms of valves and
valve gears, but this could be overcome very readily by increasing the
lead a trifle, and in my experience with these engines I find that the
practice is very general by engineers and by builders themselves to
give them a considerable amount of lead. As to the second requirement,
the maintenance of initial pressure until cut off, giving a straight
steam line, cards from this engine will not be found to show that the
engine satisfies this requirement, and for this reason, that the
cut-off valve commences to close the port immediately after the piston
commences to move.
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